/** library for Maxim DS18B20 digital temperature sensor (using 1-Wire protocol) (code)
 *  @file
 *  @author King Kévin <kingkevin@cuvoodoo.info>
 *  @copyright SPDX-License-Identifier: GPL-3.0-or-later
 *  @date 2017-2020
 *  @note peripherals used: 1-Wire (timer @ref onewire_master_timer, GPIO @ref onewire_master_gpio)
 *  @warning this library does not support parasite power mode and alarms
 */
/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdbool.h> // boolean type
#include <stdlib.h> // size_t definition
#include <math.h> // NAN definition

/* own libraries */
#include "global.h" // help macros
#include "onewire_master.h" // 1-Wire utilities
#include "sensor_ds18b20.h" // own definitions

/** remember number of DS18B20 sensors on 1-Wire bus for certain functions */
uint64_t sensors = 0;
/** remember if only DS18B20 sensors on 1-Wire bus for certain functions */
bool only = false;
/** remember code of last sensor **/
uint64_t last = 0;

void sensor_ds18b20_setup(void)
{
	onewire_master_setup(); // setup 1-Wire peripheral to communicate with sensors on bus
	sensor_ds18b20_number(); // scan for sensor (remembers sensor number and exclusivity)
}

uint64_t sensor_ds18b20_number(void)
{
	sensors = 0; // reset number
	only = true; // reset state
	uint64_t code = 0; // ROM code found (use 0 to start from scratch)
	bool more = true; // save if other additional slaves exist

	while (more) { // scan for all 1-Wire slaves
		if (!onewire_master_reset()) { // send reset to start communication
			return 0; // no slave presence detected
		}
		more = onewire_master_rom_search(&code, false); // get next slave ROM code (without alarm)
		if (0 == code) { // error occurred
			return 0;
		}
		if (0x28 == (code & 0xff)) { // family code (8-LSb) for DS18B20 sensors is 0x28
			last = code; // save last found code
			sensors++; // we found an additional sensor
		} else {
			only = false; // we found a slave which is not a sensor
		}
	}

	return sensors;
}

bool sensor_ds18b20_only(void)
{
	sensor_ds18b20_number(); // this also checks for exclusivity
	return only;
}

bool sensor_ds18b20_list(uint64_t* code)
{
	if (!onewire_master_reset()) { // send reset to start communication
		return false; // no slave presence detected
	}
	onewire_master_rom_search(code, false); // get next code
	return (last != *code); // verify if the last has been found
}

bool sensor_ds18b20_convert(uint64_t code)
{
	if (0 == code && !only) { // asked for broadcast but there are different slaves on bus
		return false; // broadcast not possible when there are also different slaves on bus
	}

	// send reset pulse
	if (!onewire_master_reset()) { // send reset to start communication
		return false; // no slave presence detected
	}

	// send ROM command to select slave(s)
	if (0 == code) { // broadcast convert
		if (!onewire_master_rom_skip()) { // select all slaves
			return false; // ROM command failed
		}
	} else {
		if (!onewire_master_rom_match(code)) { // select specific slave
			return false; // ROM command failed
		}
	}

	// send convert T function command
	return onewire_master_function_read(0x44, NULL, 0);
}

float sensor_ds18b20_temperature(uint64_t code)
{
	if (0 == code && (sensors > 1 || !only)) { // broadcast read requested
		return NAN; // this function is not possible when several sensors or other devices are present
	}

	// send reset pulse
	if (!onewire_master_reset()) { // send reset to start communication
		return NAN; // no slave presence detected
	}

	// send ROM command to select slave
	if (0 == code) { // broadcast convert
		if (!onewire_master_rom_skip()) { // select all slaves
			return false; // ROM command failed
		}
	} else {
		if (!onewire_master_rom_match(code)) { // select specific slave
			return false; // ROM command failed
		}
	}

	// read scratchpad to get temperature (on byte 0 and 1)
	uint8_t scratchpad[9] = {0}; // to store read scratchpad
	if (!onewire_master_function_read(0xbe, scratchpad, sizeof(scratchpad) * 8)) { // read complete scratchpad
		return NAN; // error occurred during read
	}

	// verify if data is valid
	if (onewire_master_crc(scratchpad, sizeof(scratchpad))) { // check CRC checksum
		return NAN; // data corrupted
	}

	// calculate temperature (stored as int16_t but on 0.125 C steps)
	return ((int16_t)(scratchpad[1] << 8) + scratchpad[0]) / 16.0; // get temperature (on < 16 precision the last bits are undefined, but that doesn't matter for the end result since the lower precision is still provided)
}

bool sensor_ds18b20_precision(uint64_t code, uint8_t precision)
{
	if (precision < 9 || precision > 12) { // check input
		return false; // wrong precision value
	}

	if (0 == code && !only) { // asked for broadcast but there are different slaves on bus
		return false; // broadcast not possible when there are also different slaves on bus
	}

	// send reset pulse
	if (!onewire_master_reset()) { // send reset to start communication
		return false; // no slave presence detected
	}

	// send ROM command to select slave(s)
	if (0 == code) { // broadcast convert
		if (!onewire_master_rom_skip()) { // select all slaves
			return false; // ROM command failed
		}
	} else {
		if (!onewire_master_rom_match(code)) { // select specific slave
			return false; // ROM command failed
		}
	}

	// read scratchpad to get alarm values (on byte 2 and 3)
	uint8_t scratchpad[9] = {0}; // to store read scratchpad
	if (!onewire_master_function_read(0xbe, scratchpad, sizeof(scratchpad) * 8)) { // read complete scratchpad
		return false; // error occurred during read
	}

	// verify if data is valid
	if (onewire_master_crc(scratchpad, sizeof(scratchpad))) { // check CRC checksum
		return false; // data corrupted
	}

	// send new configuration (and keep the alarm values)
	uint8_t configuration[3] = {0}; // to store T_HIGH, T_LOW, and configuration
	configuration[0] = scratchpad[2]; // keep T_HIGH
	configuration[1] = scratchpad[3]; // keep T_LOW
	configuration[2] = 0x1f + ((precision - 9) << 5); // set precision bit (R1-R0 on bit 6-5)
	if (!onewire_master_function_write(0x4e, configuration, sizeof(configuration) * 8)) { // write scratchpad with new configuration (all three bytes must be written)
		return false; // error occurred during write
	}

	// store new configuration into sensor's EEPROM for retrieval on next power up
	if (!onewire_master_function_read(0x48, NULL, 0)) { // copy scratchpad (to EEPROM)
		return false; // error during copy
	}

	return true;
}